Na[Tc(CO)(CN p -F-Ar DArF2 ) 4 ]: an isocyanide analogue of the elusive Na[Tc(CO) 5 ].

The first crystalline technetium complex in a negative oxidation state, [Tc -I (CO)(CN p -F-Ar DArF2 ) 4 ] - , was isolated and structurally characterized as its [Na(Crypt-2.2.2)] + salt. It mirrors the properties of the textbook organometallic compound Na[Tc(CO) 5 ], which has eluded isolation and structural characterization until today. [Na(Crypt-2.2.2)][Tc -I (CO)(CN p -F-Ar DArF2 ) 4 ] reacts expectedly as a nucleophile, which is demonstrated by reactions with HCl and ClSnMe 3 . They give the unprecedented monohydrido and trimethylstannyl complexes of technetium.